A gem of a publication semi-related to hidden hydrology by very related to cool maps, is one the US Geological Survey Miscellaneous Investigations Series I-1799, published in 1988, entitled the “Atlas of Oblique Maps: A collection of landform portrayals of selected areas of the world“. As noted, the maps are all oblique aerials, and range from 1961 to 1986, so are pre-digital. The ability to represent complex geographic and topography features enlightens many maps of this sort, and the techniques to create this makes for a fascinating read.

Some introductory text from the Preface:

There’s a brief by interesting background for the document and some of the key map-makers, including A.K Lobeck, E.J. Raisz, and P.B. King. Some of the benefits of this type of map are discussed, including more realism and easier comprehension, and ability maintain scale. Disadvantages included displacement of features, and hiding of key elements, and a relative inexactness of elevation and location. I think of many of the maps of cities in the late 1800s that were drawn using similar techniques, which show features in a compelling way, but somehow exist with a tantalizing lack of precision.

The graphic standards used are explained, which allows for some uniformity. (click to enlarge):

The mechanism of the Isometrograph was fascinating, which provides the opportunity to “develop a parallel-perspective framework from a vertically viewed contour map” allowing for three-dimensionality without reproducing hidden lines, something we can easily do today with a number of digital tools, but at the time was pretty incredible.

That said, there’s a ton of interpretation and creativity involved, to take the three-dimensional framework and convert it into a compelling illustration, as noted in the sequence below.

So why should these matter, aside from their value as historical maps. The conclusion sums it up, along with a very prescient commentary on the value and future of mapping in our current age of Google Earth:

“Because oblique maps are instructive and easy to read, they help the scientist communicate with the layman concerning our environment, especially in those areas, such as the sea floor, that are not easily accessible. With increasing population and all its attendant stresses on the planet, the need for this communication will become ever greater. Fortunately, in the near future, with new techniques and with the use of computers, the cartographer will be able to respond to this demand and create oblique maps more quickly and more economically.”

A bunch of the examples below show the range of maps – which I count over 100 total, with a vast range in geography from Alaska, Washington and Oregon, California, and many from around the world. The simplicity and elegance of the black and white showcases volcanic variants in the Pacific Northwest, two of my favorite places, Crater Lake and Mount St. Helens.

Some simple color accents coastal variation, in this case Willapa Bay in Oregon.

And the impact works as well for more urbanized zones, in this case San Francisco Bay.

The ability to use the oblique maps to carve out subsurface geology is interesting as well, in this case showing the Sierra Nevada mountains near Mono Lake.

And the bathymetry also, revealing hidden hydrology of bays and coastal waters.

The maps delve into the diagrammatic, as this one stood out to me. The image hovering above the map shows the location of underway navigation transponders in the Pacific Ocean off the coast of Mexico. The squiggly lines show the path of a ship that was mapping the bottom using sonar over multiple years.

The final section of the document highlights what are called ‘Cognitive Drawings’, which are somewhat more familiar slices of topography and geology that often appear in text-books, such as the evolution of river valley from sharper V-shapes to more subtle U-shaped valley systems.

Another hybrid map shows the relationship to the geologic features, in this case Ore deposits in Utah, with some simple accents, again revealing the underlying geological story from below.

The technical aspects of making these maps is admittedly less of a barrier today, but much of what comes from the digital realm lacks the tactile, illustrative quality shown here. A post in Landscape+Urbanism on the art of Matthew Rangel comes to mind as a similar quality in new work, and the inspiration of graphic quality and communicative value is inspiring. Worth a long perusal. Enjoy!